1. Field of the Invention
The present invention relates to a compressor having an integrated impeller and motor, and more particularly, to such a compressor used as a fan for a consumer device.
2. Description of Related Art
There are myriad different uses to which consumers can put products that create a stream of fluid. For example, U.S. Pat. No. 4,593,179 lists drying wet clothes and shoes, hydrotherapy, vacuum cleaning and drying hair. Other consumer products employing a stream of air that come to mind are space heaters, air conditioners, ventilating fans, humidifiers and dehumidifiers.
In any consumer device, noise is an important factor. A significant source of noise in any rotating machinery, such as a compressor or fan device used to create a fluid flow, is the mechanism used to provide the motive power that drives the compressor or fan. Typically, this includes an electric motor and some sort of transmission mechanism for applying the motive force of the motor to the compressor or fan.
The motor itself has rotating parts that create so-called xe2x80x9cdipole noise.xe2x80x9d In addition, vibrations induced by the motor are propagated to the surrounding area as noise by the parts of the device to which the motor is mounted. Noise is also created by the transmission mechanism connecting the motor to the compressor or fan device. For example, the motor shaft may be connected to the compressor shaft by a gearing mechanism, which is inherently noisy due to the impact of the meshing gears against each other.
The noise attributable to the transmission mechanism can be eliminated by mounting the compressor on the motor shaft. However, in an axial flow device, such as the axial flow hair dryer shown in U.S. Pat. No. 4,596,921, this on-axis motor mounting puts the motor in the duct for the compressor working fluid. That significantly cuts down on the volume fluid flow that can be pumped by the device.
Also known are motorless compressor devices, in the sense that the compressor rotor forms part of the motor. Such motors are shown in U.S. Pat. Nos. 2,629,330, 4,758,132 and 5,607,329, and in Japanese Laid-Open Application No. 2-214439. However, none of them are particularly suited for consumer devices for a variety of reasons relating to the complexity of their construction or various aspects of their manner of operation. For example, U.S. Pat. No. 2,629,330 uses direct current and would require electronics to convert regular household alternating current, thus adding significantly to the cost of the device.
It is an object of the present invention to provide a compressor or pump that eliminates the need for a separate motor, thus significantly reducing the noise generated during operation, yet is simple and economical to construct.
It is another object of the present invention to provide a compressor that does not require a separate motor to supply the motive force therefor, thus eliminating the cost of the separate motor.
It is yet another object of the present invention to provide a motorless axial flow compressor that eliminates the flow blockage of an on-axis motor mounting.
In accordance with one aspect of the present invention, a pump for transporting a fluid comprises a rotary impeller member including a plurality of impeller elements disposed for imparting kinetic energy to the fluid as the impeller member rotates, the impeller member including an electrically conductive portion, an impeller driver including a magnetically permeable stator extending in an arc proximate to a rotary path of the conductive portion as the impeller member rotates, the impeller driver including a core portion with an electrically conductive winding for inducing a magnetic field in the stator and an electrically conductive pole portion spaced from the core portion, and means for introducing alternating electrical current to the winding for imparting a rotary force to the electrically conductive portion of the impeller member.
In accordance with a more specific aspect of the invention, a pump in accordance therewith is incorporated into a hair dryer. The invention is particularly adapted for an axial flow hair dryer having counter-rotating impellers.